1. Field of the Invention
The present invention relates to a process for treatment of a fluid and to an apparatus therefor. More particularly, the present invention relates to a water treatment process for effecting a reduction in the concentration of pollutants in the fluid and to an apparatus therefor.
2. Description of the Prior Art
The treatment of fluids generally, and water in particular, to remove pollutants therefrom is a continually developing art. Development is motivated, at least in part, by the recognition that the increasing world population necessitates an increased access to water which is pollutant-reduced or substantially pollutant-free.
Generally, water pollutants can be grouped in seven classes as follows:
1. Sewage and other oxygen-demanding wastes PA0 2. Infectious agents PA0 3. Plant nutrients PA0 4. Exotic Organic chemicals PA0 5. Inorganic minerals and chemical compounds PA0 6. Sediments PA0 7. Radioactive substances
Sewage and other oxygen-demanding wastes are generally carbonaceous organic materials that can be oxidized biologically (or sometimes chemically) to carbon dioxide and water. These wastes are problematic since: (i) degradation thereof leads to oxygen depletion, which affects (and can even kill) fish and other aquatic life; (ii) they produce annoying odours; (iii) they impair domestic and livestock water supplies by affecting taste, odour and colour thereof; and (iv) they may lead to scum and solids that render water unfit for recreational use.
Infectious agents are usually found in waste water from municipalities, sanatoriums, tanning and slaughtering plants and boats. This type of pollutant is capable of producing disease in man and animals, including livestock.
Plant nutrients, (e.g. nitrogen and phosphorus) are capable of stimulating the growth of aquatic plants, which interfere with water uses and which later decay to produce annoying odours and increase the amount of oxygen-demanding waste in the water (see above).
Exotic organic chemicals include surfactants used in detergents, pesticides, various industrial products and the decomposition products of other organic compounds. Some of these compounds are known to be toxic to fish at very low concentrations. Many of these compounds are not readily biologically degradable.
Inorganic minerals and chemical compounds are generally found in water from municipal and industrial waste waters and from urban runoff. These pollutants can kill or injure fish and other aquatic life, and can also interfere with the suitability of water for drinking or industrial use. A prominent example is the occurrence of mercury in water. Another example is salt pollution from NaCl and CaCl.sub.2 used to de-ice roads in winter in the northern, colder climates.
Sediments are soil and mineral particles washed from the land by storms and floodwaters, from croplands, unprotected forest soils, overgrazed pastures, strip mines, roads and bulldozed urban areas. Sediments fill stream channels and reservoirs; erode power turbines and pumping equipment, reduce the amount of sunlight available to aquatic plants; plug water filters; and blanket fish nests, spawn, and food supplies, thereby reducing the fish and shell fish populations.
Radioactive substances in water environments usually result from the wastes of uranium and thorium mining and refining; from nuclear power plants and from industrial, medical, scientific utilization of radioactive materials.
While the prior art is replete with processes and apparatus for treatment of water, a particularly advantageous process and apparatus for treating water containing pollutants is disclosed in U.S. Pat. No. 5,108,563, the contents of which are hereby incorporated by reference. This patent describes electrolytic treatment of water using an electrode comprising a particular arrangement of electrodes.
Whereas the process and apparatus disclosed in the '563 patent have attained a certain degree of success, it would be desirable if the design could be optimized to improve the efficiency of water throughput without substantially compromising reduction of the pollutants contained in the water.